DESCRIPTION (Applicant?s Abstract): There are 10 aims for this project involving two different lines of research. We propose to do the following: (1) to investigate the effects of three levels of weight reduction (0 percent, 10 percent, and 20 percent) on rate of acquisition and asymptotic performance on a two-lever drug discrimination task with gamma-hydroxybutyrate (GHB) vs. saline; (2) To test the discriminative stimulus properties of GHB, gamma-butyrolactone (GBL), flunitrazepam (Rohypnol), and ethanol; (3) To investigate discriminative stimulus properties of GHB and GBL when given as mixtures with ethanol; (4) To partially replicate and extend preliminary results on the effect of reinforcer type on the development of tolerance to reinforcer magnitude; (5) To determine the extent to which reinforcement context affects the development and degree of tolerance to amphetamine and morphine; (6) To determine the extent to which reinforcer magnitude affects the development and degree of tolerance to amphetamine and morphine; (7) To elucidate the role of behavioral variables in modulating the behavioral effects of drugs and to highlight their potential for the treatment of drug abuse; (8) To write a comprehensive review of the literature on the status of the concept of state dependent learning (SDL) vs. drug discrimination, to seek feedback from the few existing SDL researchers, and publish in a review journal; (9) To design experiments to partially replicate and extend our research with the Maier 3-table reasoning problem to determine whether rats that demonstrate a performance deficit when experiences are given under morphine and saline demonstrate similar deficits when tested with combinations of methadone and saline or buprenorphine and & saline; and (10) To expose high school, undergraduate, and graduate minority students to a variety of research methods used in behavioral pharmacology in order to prepare them for admission to and retention in excellent graduate research programs and, potentially, drug abuse research careers. Students will be involved in every aspect of this research including research ethics, animal care and handling, animal behavioral testing, data analysis, library research, literature review, and preparation of papers for presentation and publication.